count occurrences of arrays in multidimensional arrays in python

Question

I have the following type of arrays:

a = array([[1,1,1],
           [1,1,1],
           [1,1,1],
           [2,2,2],
           [2,2,2],
           [2,2,2],
         


        

Answer 1

The numpy_indexed package (disclaimer: I am its author) contains efficient vectorized functionality for these kind of operations:

import numpy_indexed as npi
unique_rows, row_count = npi.count(a, axis=0)

Note that this works for arrays of any dimensionality or datatype.